In less than a year after becoming operational, and still in its trial phase, the Five-hundred-meter Aperture Spherical Telescope (FAST) in southwest China has found two pulsars, the National Astronomical Observatories of China (NAOC) announced Tuesday. The discoveries, made in August, were confirmed by another radio telescope in Australia.
The two pulsars are relatively close, on the cosmic scale, at a distance of only 16,000 light-years and 4,100 light-years from Earth. Named J1859-01 and J1931-01, they have rotation periods of 1.83 seconds and 0.59 seconds respectively.
Pulsars are highly magnetized neutron stars that rotate really fast, up to hundreds of times a second, with short and regular rotational periods. They are only a few miles across — a fraction of the size of the stars that collapsed to become pulsars, which had between seven and 20 solar masses — but are extremely dense and their solid surfaces have temperatures of about one million degrees.
First discovered accidentally 50 years ago, over 2,000 pulsars have been found so far, but there is still a lot we don’t know about them, such as what exactly is inside them. From the outside, however, their radiation seems to a distant observer to be pulsating regularly — something like the regular sweep of a lighthouse beam — giving them their name.
Studying pulsars has multiple applications, from using the precise period of certain types of pulsars to keep time more accurately than atomic clocks to understanding space-time and the behavior of gravity around supermassive black holes by studying how pulsars orbit the one at the center of Milky Way. They can also be used to detect gravitational waves.
Chief scientist at NAOC, Li Di, told Xinhua the two new pulsars were discovered Aug. 22 and Aug. 25 during a drift-scan of the southern galactic plane by FAST, and that confirmation was made by the 64-meter Parkes radio telescope in Australia in September.
“It is truly encouraging to have achieved such results within just one year,” Peng Bo, deputy director of the FAST project, told Xinhua, adding it usually took a radio telescope of similar size and complexity between three and five years to complete trial operations. FAST will likely go through another two years of trial runs, so that any potential problems can be ironed out.
Located in a deep karst depression in a mountainous region in southwest China, FAST — nicknamed Tianyan (Chinese for “Heavenly Eye”) — is partially naturally shielded from radio frequency interference. Detection of pulsars is one of its primary scientific objectives, but scientists hope the telescope would also lead to expanding “the total volume of knowledge of compact objects, gaseous galaxies, and interstellar medium,” according to FAST’s website.
FAST, the world’s largest single filled-aperture radio telescope, began operations Sept. 25, 2016. China has a very ambitious space program and its astronomy-related installations on the ground reflect that. Other than FAST, the country is also working on the construction of the world’s highest-altitude telescope to detect gravitational waves, at a height of over 17,000 feet above sea level, in the sparsely populated Tibet.